Lately I've been seeing 9-10 Degrees of knock retard and it's really annoying to have no power. Can gunked up valves at 82k cause it?

 

What gas u using. And possibly. Also a clogged cat can cause it to.

 

I always use 91. At QT usually. I do have my brother's spare stock downpipe he got at like 40k miles. I looked at it and it looked pretty clean.

 

well how long ago has this been going on? since last fill? its possible that the station filled the 91 with a lower grade. id try filling somewhere else to test that theory. iv seen it happen.

 

i've been told by a fuel truck driver i know that they do this.

 

if id ever catch them, which it is easy when ur monitoring knock and such, I would go into that station, ask for the manager and give them hell.

 

your crappy gm tune probaly went "bad" lulz

 

lulz

 

you guys are bad

 

I thought more boost meant more power?!

 

me too.

 

More airflow means more power. Boost to but only to a point . If ur turbo can't push enough air u can boost to 100 if u want it won't do nothing but melt ur engine lol

 

A new head has fixed my knock.

I had 2-4 degrees consistently on low rpms when initially driving. Also, I would get very occassional 8-10 degrees in the first five minutes if I didn't drive it as slow as possible haha.

One day it clicked that it was the valves causing it. I had to pull out into busy traffic and the car wasn't warmed up, probably hit a couple lbs of boost nothing crazy. Well I noticed the knock go up to 11 degrees and felt as if I was getting no airflow. When I drive away at the stop light, all of sudden the car "breathes" and the knock goes back down to it's normal 2-3 degrees at the beginning.

08 ss/tc with 90k at the time. No more than 1.5 degrees very occassionally since the change 3k ago. my intake valve on #2 had so much gunk the valve couldn't seat properly and was constantly getting stuck. The process of removing intake mani to just look at valves was a complete pain but completely worth it to see how my valves really were. I also had random misfire codes that would show up on aeroforce but not check engine light except for the story above caused a light for a couple days (even had a p0302 which went with the most coked valve). Parked it and waited on the new head and arp head studs from zzp, and ordered slightly used rockers and lash adjustors from jreiland.

Long story short, good luck and check out those valves!

 

So you put a whole new head on instead of cleaning the valves?

For $100 and a day of work you could have cleaned them yourself. Hell you took the manifold off already. All you had to do was clean and see if it cleared up.

Unless your valve seats were screwed up of course.

 

That was the worry, this was my first rodeo with an engine head and the valves were really bad (worst than any pic i've seen here). One had gunk from the wall to the middle of the stem, that thing was barely moving if at all. Didn't want to do all the work of cleaning them when there was a good chance the valve guides or valve seats were screwed up and it costing me an extra day and $100 on walnut blasting stuff.

 

So weird how gunk buildup is horrible for some while non-existent for other's.

 

It's not non-existent. I think a lot of people let it go unoticed. I could only feel mine in the seat during the winter. Cleaned at 75k and they were awful. Took a long time but between blasting and top end cleaner, it woke the car up nicely.

 

mine was kind of gunky but not too bad. Even at 96k miles.

 

Really u changed ur head instead of just walnut blasting them which would have cost u like 50 bucks? That's kinda a bad choice u made there

 

Mine were not to bad At like 30k kms. Just stained black no gunk, blasted them anyway. Powell oil seperator ftw. It doesn't stop everything though, noticed a small amount in my intake other day. Nothing like it used to be though